WASHINGTON (CNN) --The latest tape purported to be from Saddam Hussein shows an effort to reassure his followers he is alive as coalition forces try to track him down, according to a former acting U.S. ambassador to Iraq.

The tape was aired Tuesday on the Arabic-language network Al Arabiya. On it, the speaker mourns the deaths of Saddam's sons Uday and Qusay Hussein, whom U.S. forces killed last week in the northern Iraqi city of Mosul. (Gallery: Timeline of the attack)

Besides being an "effective confirmation" of the sons' deaths -- more convincing than the images of the bodies released last week to offer Iraqis proof the two were dead -- the tape's existence indicates Saddam is trying to prove his influence, the U.S. diplomat, Joseph Wilson, said Tuesday.

"I think he's trying to reassure his followers that he's still alive and that he's still rebelling and trying to confront this occupation," Wilson said.

"It'd be interesting to see if in fact the United States really is closing in on him. I wouldn't be surprised. It looks to me like some of the cells surrounding him and protecting him may be breaking down."

The tape's speaker said, "The souls of great people have been elevated as martyrs and returned to its creator. They are like precious birds in the presence of merciful God."

The tape also referred to the death of Qusay's teenage son, Mustafa, in the U.S. firefight.

"Your brothers Uday, Qusay and Mustafa, the son of Qusay, have all stood a great fight as believers in Mosul. After a hard fight against the enemy lasting six full hours, the enemy could not get to them after surrounding them with all its equipment until they fired missiles via airplanes."

The speaker then said: "If Saddam Hussein had the option to sacrifice other sons other than Uday and Qusay, Saddam Hussein would have sacrificed them the same honorable way.

"It is our duty. It's a duty on every believer. Our freedom and patriotism call upon every believer to sacrifice themselves. We must be of those believers who make history and testify to our bravery."

U.S. forces early Tuesday captured a one-time bodyguard and two other Saddam associates in Tikrit, the ancestral hometown of the former dictator where he still enjoys strong support. A senior U.S. official said the bodyguard had not seen Saddam or been close to him in months.

U.S. officials said the captures are evidence the United States is moving ever closer to Saddam.

"Now you've got Saddam in a position where he's either been flushed or he's been forced to go back [underground]," Wilson said. "And if he's been flushed, and if he's running around every two hours as they say, then presumably he's just a couple of steps ahead of the coalition forces."

Wilson said he wonders why Qusay and Uday were found in northern Iraq, where support for the former regime was never robust.

"It strikes me as either they were flushed from a previous hiding place, or else they were so confident that they really just gave up some basic security," Wilson said. (Profiles: Qusay Hussein, Uday Hussein)

Wilson said that Saddam's best chance to survive may be to go back to Baghdad's sprawling neighborhoods, some of which are impenetrable to U.S. forces, especially those trying to move in clandestinely.

"Any American movements in some of these neighborhoods would be well telegraphed ahead of time," he said.

"You know, you have 150,000 Americans in hostile territory, and you're going to see an indigenous resistance that I think actually will grow and will not abate, even if Saddam is caught and captured or killed."

Since President Bush declared an end to major combat on May 1, 49 U.S. troops have died in hostile action in Iraq. A total of 247 U.S. troops have been killed since the Iraq war began in March. (Interactive: U.S. deaths)

Wilson recently was at the center of the controversy over discredited information used in Bush's State of the Union address.

In an opinion piece this month for The New York Times, Wilson said the CIA asked him to investigate the allegation that Iraq was attempting to buy nuclear materials from Niger and he reported back that it was inaccurate. He said he did so almost a year before the president, citing British intelligence, alleged that Iraq was trying to purchase uranium from Africa. The White House has said the claim should not have been included in the State of the Union address.